The polyphenylene ether resins are a family of engineering theromplastics that are well known to the polymer art. These polymers may be made by a variety of catalytic and non-catalytic processes from the corresponding phenols or reactive derivatives thereof. By way of illustration, certain of the polyphenylene ethers are disclosed in Hay, U.S. Pat. Nos. 3,306,874 and 3,306,875, and in Stamatoff, U.S. Pat. Nos. 3,257,357 and 3,257,358. In the Hay patents, the polyphenylene ethers are prepared by an oxidative coupling reaction comprising passing an oxygen-containing gas through a reaction solution of a phenol and a metalamine complex catalyst.
U.S. Pat. No. 3,356,761 discloses such polyphenylene oxides which are dissolved in styrene monomer and the styrene monomer subsequently polymerized into polystyrene to produce a mixture of polyphenylene oxide and polystyrene.
U.S. Pat. Nos. 3,373,226 and 3,383,435 disclose mixtures of polyphenylene oxide and a styrene resin.
U.S. Pat. Nos. 3,660,531 and 3,920,770 disclose polyphenylene oxide, or styrene resin modified-polyphenylene oxide, and a rubbery polymer, such as, for example, a butadiene-styrene block copolymer, said blends having unexpected thermoplastic properties.
U.S. Pat. Nos. 4,139,574 and 4,143,095 describe compositions comprising polyphenylene oxide and butadiene-styrene teleblock copolymers. Impact strength and surface gloss are mentioned as improved properties of articles molded from such compositions in these patents.
Although the incorporation of rubbery copolymers into polyphenylene oxide compositions has been found to be desirable to improve certain properties of such compositions one typically encounters further problems. Specifically, lamination effects in compositions of polyphenylene oxide and rubbery polymers constitute a serious problem. Lamination is undesirable since it causes weakness of molded articles and can cause surface blemishes (undesirable surface appearance). The lamination is believed to relate at least partially to the incompatibility of the rubbery copolymer and the polyphenylene oxide. This is evidenced by a layered-structure appearance which is most evident at a fractured edge. This problem has now been solved in accordance with this invention by the incorporation of a linear or radial rubbery teleblock copolymer into the polyphenylene oxide composition, which teleblock copolymer has blocks of polymerized monovinylarene at the free ends of the polymer chains, said blocks having a high heterogeneity index.
It is thus one object of this invention to provide a thermoplastic polymer blend with improved properties, particularly with improved lamination properties.
A further object of this invention is to provide a polyphenylene oxide composition having good mechanical properties such as tensile and impact strength rendering it useful as an engineering resin and having no serious lamination problems.
Yet, another object of this invention is to provide a blend of polyphenylene oxide and rubbery polymers with good heat distortion and tensile properties at elevated temperatures.
Other objects, aspects, advantages, features and embodiments of this invention will become apparent to those skilled in the art from the following description and the appended claims.